The present invention relates to an X-ray source in general and, more particularly, an X-ray source for generating a small X-ray beam toward a small area of a specimen to be examined, suitable for an X-ray photoelectron spectroscopy (XPS) or an X-ray fluorescence spectroscopy, or an X-ray lithograph.
Conventionally, it is very difficult to focus the diameter of an X-ray beam in the order of, for example, 100 .mu.m or less. Some attempts have been proposed as described below with reference to FIGS. 6-9. In an X-ray source of FIG. 6, an electron beam 2 is emitted toward a target 4, so that part of X-ray beam 6 generated from the target 4 are focused using a spherical spectroscopic crystal 8. In the X-ray source of FIG. 7, part of the X-ray beams 6 generated from the target 4 in response to the irradiation of the electron beam 2 are focused using a cylindrical total reflection surface 10. This surface 10 serves to totally reflect the part of the X-ray beams 6. With reference to the X-ray source of FIG. 8, part of the X-ray beams 6 generated from the target 4 in response to the irradiation of the electron beam 2 are focused with the diffraction phenomenon using Fresnel zone plate 12. Further, with reference to FIG. 9, a specimen 14 is closely binded with a thin film target 16. The electron beam 2 is applied to the thin film target 16 in an attempt to produce the X-ray beams 6 from a small point of the thin film target 16.
In the above-described X-ray sources of FIGS. 6 to 8, only part of the X-ray beams 6 generated from the target 4 are focused with the spherical spectroscopic crystal 8 or the zone plate 12 while the other part of the X-ray beams are astray. Therefore, it is difficult to provide strong X-ray beams of small diameters.
Further, in the X-ray source of FIG. 9, the thin film target 16 and the specimen 14 must be closely found so that this type of X-ray source should be limited to a specific purpose, for example, in which the thin film target 16 is used to be exposed to the electron beam 2, whereby the X-rays 6 are emitted from the opposing side to the thin film target 16.